In cardiac surgery, a quiet, bloodless operative field is attained by the use of cardioplegic agents. These solutions are injected into the heart while the aorta is clamped to decrease myocardial metabolism and eliminate contraction of the muscle. These solutions protect the heart from damage during the period of ischemic arrest. We have developed a new method for regional infusion of cardioplegic agents during the period of ischemic arrest by selective perfusion of the anterior descending and the circumflex coronary arteries with two different cardioplegic solutions. Ultrasonic crystals are used to assess regional function and compliance after the ischemic period. We have completed a project assessing the pressure at which cardioplegic solutions may safely be infused into the aorta. This study has indicated that pressures up to 150 mm Hg. may safely be utilized. We are currently evaluating calcium antagonists as an adjunct to cold cardioplegic myocardial preservation. We plan to study other drugs which have been shown to be useful in myocardial infarction. These drugs may also be useful adjuncts to cold cardioplegic protection of the heart in cardiac surgery.